1. Technical Field
Embodiments of the invention relate generally to structures for directing an optical signal in a photonic device. More particularly, certain embodiments relate to a reflector die for reflecting an optical signal into a photodetector for generating a corresponding electrical signal.
2. Background Art
Architectures for photonic devices often rely upon a silicon-layer-waveguide-based approach in which a planar silicon layer of a substrate functions as a waveguide to carry an optical signal. Due to the absorption qualities of silicon, such approaches can only be implemented for a limited range of optical signal wavelengths. For example, silicon layer waveguide structures are compatible with larger wavelength optical signals—e.g. lasers having wavelengths around 1310 nm. However, smaller wavelength optical signals—e.g. in the range of 850 nm—cannot be effectively exchanged, due to silicon's absorption coefficient at such wavelengths.
In these photonic device architectures, such a range of wavelengths can also constrain the use of photodetectors to convert optical signals into corresponding electrical signals. Photodetectors such as normal incidence photodetectors (NIPDs) may be fairly readily used for lasers operating in the 850 nm range, for example. However, for larger wavelength—e.g. 1310 nm—lasers, an NIPD's active area must be much smaller to achieve high-bandwidth performance at such larger wavelengths. For such larger wavelength signals, the required precision for aligning optics (e.g. lens, mirror, etc.) with such a small active area of a photodetector has been very difficult to achieve in volume.